Various homepages by shops that sell commodities and so on are opened on the Internet. In such online sales, the payment of the price for the commodities and the like may be carried out by, for example, the bank transfer, postal transfer, cash on delivery, or credit card. Normally, since the communication between the shop server and customer terminal is encrypted by Secure Socket Layer (SSL) and the like in the case of the credit card payment, there must be no case where other people can peep. However, typical customers do not prefer inputting the credit card number for each order of the commodities and the like. On the other hand, if they have to carry out the bank transfer or postal transfer every time, there is a problem where they must spend time and effort and must pay remittance charges. Especially, in the case of C.O.D., the charge for C.O.D. is expensive.
Therefore, a system for exempting from sending the credit card number for each order on the Internet is used. For example, a customer registers the credit card number in a settlement business company in advance by post and the like. When he or she purchases commodities and the like on the homepage of a shop that ties up with the settlement business company, the settlement processing of the order price is carried out by cooperating the shop and the settlement business company and performing customer authentication for the customer by the settlement business company.